US737974A

US737974A - Screw-machine.

Info

Publication number: US737974A
Application number: US9370102A
Authority: US
Inventors: Frank L Todd
Original assignee: Individual
Current assignee: Individual
Priority date: 1902-02-12
Filing date: 1902-02-12
Publication date: 1903-09-01
Anticipated expiration: 1920-09-01

Description

N0.'737,97 4. PATENTED SEPT. l, 1903.

' F. L. TODD.

SCREW MACHINE.

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SCREW MACHINE.

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No. 737,974. PATENTED SEPT. 1,1903. F. L. TODD.

SCREW MAGHINE.

APPLICATION FILED FEB. 12. 1902.

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UNITED STATES Patented September 1,1903;

FRANK L. TODD, OF ELYRIA, OIIIO.

SCREW-MACHINE.

lE'ECZFIGATIGN forming part of Letters Patent No. 737,974, dated September 1, 1903. Application filed February 12, 1902. Serial No. 93170 0 modem To aZZ whom, it may concern:

Be itknown that I, FRANK L. TODD, a citizen of the United States, residing at Elyria, in the county of Lorain and State of Ohio, have invented a certain new and useful Improvement in Screw-Machines, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings.

My invention relates to automatic screwcutting machines; and my object is to produce a machine of this class which shall be of very simple construction, but at the same time efficient in operation.

A further object has been to produce a machine in which the work may come simultaneously or successively under the influence of different tools without involving the use of the turrets often found in machines of this class.

The invention consists in a certain construction of parts and combinations thereof, to be more fully described hereinafter and definitely set forth in the claims.

Before proceeding to adetailed description of this invention it may expedite matters to outline its general construction.

The machine consists, then, of a frame adapted to support a spindle very similar to those found in lathes and carries a shaft eX- tendinglongitudinally of the machine, which shaft is provided with certain cams and is continuously driven so that these cams operate through other mechanism to advance and withdraw the tools from the work, cooperating in such a manner that all the operations are automatic and rapidly effected.

One of the features of this machine lies in the construction of tool-carrying mechanism, which in a sense displaces the turret used in machines of this kind. This consists substantially of a guide extending laterally on the machine, upon which guide is mounteda carriage with several tool-heads, which heads are adapted to slide upon the carriage longitudinally of the machine, and mechanism is provided whereby these heads carrying difl.'erent tools, as they do, may be brought successively into operation upon the work. Other features of the machine lie in the methods of driving these parts and of bringing about the automatic operations mentioned.

In the drawings, which fully illustrate my invention, Figure 1 represents a side elevation of the same. Fig. 2 represents the machine in plan. Fig. 3 represents an end elevation on an enlarged scale and showing some parts in section to more fully disclose their construction and relation. Fig. etrepresents a transverse vertical section taken on the line a 4 of Fig. 1. Fig. 5 represents another vertical section taken on the line 5 5 of Fig. 1. Fig. 6 represents, 011 a much enlarged scale, a longitudinal section on the line 6 6 of Fig. 2. Fig. '7 is a vertical section taken on the line 7 7 of Fig.8. Fig. 8 is a vertical section on the line 8 8 of Fig. 2, and Fig. 9 is a vertical section on the line 9 9 of Fig. 2; and Fig. 10 is a section on the line 10 10 of Fig. 3, some parts being omitted for the sake of clearness.

Referring to the parts by letters, A represents a frame, the general construction of which is disclosed in Figs.l and 2. It comprises upright members a, adapted to carry a horizontal shaft 13, which shaft, it will be observed, extends continuously from end to end of the machine. This frame is surmounted by a housing a, in which is carried a usual form of hollow spindle O, which is provided with a chuck 0, adapted to clamp the work. The form and construction of this chuck forms no part of this invention, and it may be of any of the well-known forms known as automatic in the art. Such chucks, it will be remembered, are provided with stock-feeding mechanism and mechanism for closing the chuck to grasp the work. Downwardly-pro jecting pins 0 0 respectively operate the feed ing mechanism and the chuck aforesaid, and I provide means for moving these pins so that the feeding of the stock and closing of the chuck occur at the proper time. This I accomplish by means of the cam-wheel 11 upon which are mounted the cams 6 b I1 19 Instead of securing these cams directly to the cam-wheel I prefer to mount them all upon an auxiliary section or shell I), which fits over and is removably secured to the wheel 11 by screws 19 and the arrangement of these cams upon the shell is intended to cause certain predetermined movements of the feeding and chucking devices, and I may have several of these jackets with di fit'erently-arrangod cams,

ii I 737,974

each arrangement correspon ding to a different kind of work. here a change is made to a new class of work it will then not be necessary to readjust all the cams upon the camwheel, but simply to remove the shell then being used and substitute one with that arrangement of cams adapted to the new class of work to be done. This arrangement effects a great economy of time. As the cam-wheel b rotates, the pin 0 contacts first with the cam 11 and then with the cam 13 one of which cams operates to open the chuck and the other to close it. Similarly the cams b operate upon the pin 0 so that the stock is periodically grasped, fed forward within the chuck,and then released again after the chuck has clamped it. The feed-cam b is adapted for adjustment, as shown, being pivoted at Z) and provided with a bolt 1), riding in a circumferential slot b provided in the shell. The broken section at the bottom of this camwheel indicates the method of securing the jackets in position, where it will appear that they are provided with marginal flanges Z1 which lie over the edges of the cam-wheel.

Provision is made for driving the spindle O in either direction by means of the vertical shaft D, which carries the bevel-gear d, meshing with bevel-gears c 0 which are loosely carried upon the spindle C. These bevel-gears are provided with clutch-teeth c and a sleeve 0*, which is feathered to the spindle O and provided with corresponding clutch teeth, may be slid into engagement with either of said bevels, wherefore the spindle C will be rotated in the same direction as the bevel with which this sleeve is in engagement, as will be readily understood.

In many classes of work adapted to be performed upon this machine it will be found necessary to drive the spindle only in one direction, in which case the sleeve 0 will be allowed to remain in engagement with either of the bevels as desired, but I provide means for reversing the direction of this spindle automatically at any intervals desired. This is accomplished by the slide 0 which projects up into the shifting-collar c on the aforesaid sleeve o affording means for sliding the same when it is itself moved in a horizontal guide ((5, in which guide it is slidably mounted in the frame; This slide 0 projects downwardly, as shown, at one end, where it is provided with a small friction-roller 0 which roller is adapted to be engaged from time to time by cams I), mounted upon a disk Z), carried by the aforesaid shaft B. There may be as many of the cams as desired, and they are adjustably connected to the disk Z) in any suitable manner, wherefore reversals of the spindle 0 take place at the proper intervals.

The lateral guide E, referred to in the general description and clearly shown in Figs. 1 and 2, supports a carriage e, which, it will be understood, is adapted to slide from side to side of the machine upon said guide E. In this carriage e are mounted a plurality of toolheads 6, preferably four, as shown, which are guided thereupon, so that they may slide in parallelism with the axis of the aforesaid spindle 0. Each of these heads is adapted to carry a cutting-tool, and mechanism will be described by which they may be brought successively into operation upon the tool and returned automatically to their normal position, in which position they are shown in Figs. 1 and 2. the point at which these toolheads are guided the carriage eis provided with abore E which extends nearly through the same and affords means for housing a helical spring F, which thrusts against the bottom 6 of this bore, as indicated in Fig. 2. The outer portion of this spring F envelops an arbor 6 which projects a slight distance within the aforesaid bore and is mounted rigidly at its outer end in the extremity of the aforesaid guide E. This spring affords means for normally maintaining the carriage e in the position shown in Fig. 2, in which it abuts an adjustable stop 6 and also operates to return the carriage to this position when the same has passed from the control of certain mechanism affecting a transverse movement of the same. This transverse movement is brought about by means which will be now described.

From an inspection of Fig. 4 it will be seen that the carriage e is provided with downward extensions or bosses 6 as shown in dotted lines in Fig. 4, and each of these bosses carries a frictionroller e Beneath the heads is mounted transverse auxiliary shaft G, which is driven from the main shaft through the bevel-gears q g g b and carries a camwheel g, upon which cam-wheel are mounted adj ustably certain cam-plates g,.which as the shaft rotates are brought into contact with the aforesaid rollers e. The disposition of these cams is preferably such that the slide a ismoved first an amount necessary to aline the nearest of the several heads first. After this head has finished its out upon the work the carriage is moved again, so that the next head is brought into alinement, and so on. I provide means for locking the slide in each of these successive positions which it must assume. Before proceeding to a description ofthis locking mechanism it may be expedient to say that there are three of the cams g, and they operate simply to advance the slide, the same being always returned by the spring F, as aforesaid. I provide three additional cams g and these are arranged at proper positions upon the same cam-wheel g. Their purpose is to prevent the spring causing too sudden a return of the carriage e. As the spring returns the carriage the aforesaid rollers (2 contact successively with these cams 9 much in the same manner as they did with the other cams to advance the carriage. The return of the carriage is thus retarded and progresses with the rotation of the cam-wheel However, for the sake of economy of time in opera-tin g the machine the engaging faces of It will be observed that well below these cams may be set at a very slight incline, so that the time consumed in returning the carriage is quite short. All of these cams may be secured upon the cam-wheel substantially in the manner shown in the section of the cam-wheel in Fig. i, wherefore it will appear that they may be set and secured with any angle intervening between them that may be desired and secured at any point whatever upon the periphery. It will be evident from the construction of this cam-wheel and the great freedom possible in the attachment of the cams to the same that the carriage E could be given a succession of movements in either direction at will, wherefore if it were desired to apply that tool carried by the third head for instance, before that carried by the first or second heads-this would be perfectly expedient'and feasible, and indeed the tools may be applied in any order whatever desired by a corresponding arrangement of the cams. However, in most operations it will be found more economical of time to arrange the tools in the heads so that they would be applied to the work in the order described, and in some cases where the work accomplished is very simple it may perhaps be only necessary to make use of the tools in the first and second heads.

As to the locking mechanism and referring especially to Fig. 4, it will be seen that the lower face of the slide 6 is provided with a series of recesses e preferably four in number, (shown in dotted lines,) and a bolt ll, guided vertically in the frame A, is normally constrained upwardly by a helical spring h in the position shown in Fig. 4, in which the first tool-head alines with the work. The upper extremity of this bolt H lies within the innermost of these recesses, and evidently such a relation of the parts locks the carriage e in the position shown. Before the carriage is moved by the cams g this bolt H is withdrawn and allows the carriage to pass uninterruptedly across the machine above it. When, however, the carriage has moved far enough for the next of the tool-heads e to aline with the spindle O, the spring it throws this bolt ll into the recess which is then above it, thereby locking the carriage 0, so that proper alinement is established for the tool in the head to do its work. The mechanism for withdrawing this bolt to allow the movement of the carriage is also most clearly shown in this same Fig. 4:, where it will appear that the shaft 13 is provided with a cam-disk b to which three cams Ifare adj ustablysecured. Each of these cams is provided with an inclined face I)", adapted to contact with a small roller h, carried by the lower extremity of the aforesaid bolt II, wherefore the bolt H may be drawn down and held down by the circumferential face 12" of this same cam. These cams are so disposed about the periphery of the cam-disk that the bolt H is withdrawn, as described, by the foremost of these cams just at the moment in which the trans- I provide upon the cam-disk b an additional cam Z2 which is substantially similar to those described, except that it is longer. The purpose of this cam is to withdraw the bolt and rest-rain it during the time in which the carriage is being returned by the spring F, but as the time consumed in returning the carriage may be comparatively short the length of this returning-cam need not be very great. These cams are adj ustably secured to the disk 11 wherefore they may be disposed about the periphery of the same as desired. Longer or shorter cams may be arranged in various orders as may be necessary to accomplish changes in the order of application of the different tools carried by the head to the work, if such a change of order is desired. The selection and arrangement of the cams would be similar to that mentioned in describing the manner of advancing the carriage in order to apply the heads carryin g the tools in a changed order.

Mechanism is provided for advancing the centrall -alined head at the proper time, so

that the tool which it carries may reach and operate upon the work. Referring especially to Figs. 1 and 2, it will appear that at the rear of these heads the frame of the machine is provided with a guide K, in which is mounted a tail-slide 71;. This slide is somewhat similar in construction to the tail-stock of a lathe except that instead of a tail-center there is mounted therein a threaded screw or plunger it, which is provided with a hand-wheel k for turning the same to effect a proper adjustment. The slide 7c, being split at 70 as indicated, and provided with a bolt I0 affords means for clamping the screw 71') immovably after it has been properly adjusted. As will appear from the description following and as shown in Figs. 1 and 2, the tip 70 of this screw is adapted to contact with the rear face 0 of any of the tool-heads e, and mechanism is provided for advancing the slide 7c so that the centrally-alined head can be advanced, the proper amount to bring its tool into operation upon the work. The purpose of the adjustment for the tip L is apparent. I provide mean s for advancing this tail-slide 7; by means of a cam-wheel Z), mounted upon the main shaft B and adj ustably carrying certain cams U, which cams cooperate with the frictionroller is, carried by the downward extension k on the slide it. There should be several of these cams, so that the several heads may be advanced. In Fig. l a portion of this camwheel Z) is shown in section, and it appears that its periphery is provided with circum- ICC IIO

ferential grooves 11 in which are slidably mounted blocks 7), integral with the cams b aforesaid. A central T-slot h affords means for securing the cams in position, and laterally projecting bolts I) afford means for clamping the blocks at the inner ends of the cams within the inner slot. A helical spring 7& (shown in dotted lines in Fig. 1) affords means for normally constraining the slide in its rearmost position, where it abuts against the small set-screw a, which affords means for adjusting its position, and this spring also affords means for returning this slide it after it has passed from under the influence of the cams b These cams, however, only operate to advance the heads and have nothing to do with their return to the normal position. Thereturn is effected by mechanism now to be described.

Referring especially to Figs. 1 and 5, it will be observed that a tool-head-returning plunger L is mounted horizontally below the spindle C, where it is suitably guided in the frame of the machine and provided at its outer eX- tremity with a friction-roller Z. A helical spring Z" normally constrains it into an extreme position. To the extremity of this plunger is adj ustably secured a dog Z which dog, as clearly shown in Fig. 5, is provided with a vertical extension or toe Z This toe is adapted to contact with the forward extremity of the heads e in order to effect their return to normal position within the carriage 6. At proper intervals cams b carried by the cam-wheel 11 upon the shaft B, cooperate with the aforesaid friction roller 1 to bring about this result. The tool-head-returning plunger L is returned by the spring Z to its normal position, in which position it is shown in Fig. 1. These cams b are provided with faces I), inclined oppositely to their drivingfaces, wherefore a too sudden return of the plunger L is prevented in a manner well understood.

It will be readily seen from the description of the mechanism for advancing the centrallyalined head which advances the tool-head and from the description of the plunger L, just described, that the distance which the tool-head is advanced when in line with the advancing mechanism can be regulated so that it will be just sufficient to do the work required and the plunger mechanism so adjusted relative thereto that the head will be immediately returned when the operation of the tool in the head is completed.

Up to this point the description has been concerned principally with outlining the mechanism employed in operating those tools carried by the tool-heads 6'. However, I provide another system of mechanism for bringing up tools so that they may operate upon the work from the side. These tools may comprise forming and cutting-off tools.

Referring especially to Figs. 1 and 5, it will be observed that the frame at a point substantially beneath the position of the work is provided with a guide (L in which guide a slide M is adapted to move transversely of the machine. Upon this slide is mounted a table m, adj ustably held between bolts m, carried by the aforesaid slide, and this table is provided with the common T-slots m in which slots tool-posts (not shown) are adapted to be mounted. Mechanism is provided for moving this slide M automatically, so that the tool on either side may be brought into operation upon the work. For that purpose at this point the frame A is provided with two oppositely-projecting arms (0*, to which arms are pivoted levers N. These levers are provided at their extremities with friction-rollers n, adapted to contact with cam-plates I) I), carried by the cam-disk 0 which is mounted upon the aforesaid main shaft 13. These levers N are pivoted, as shown, at a and at the same points a are pivoted other levers O. The levers N are each provided with a substantially radial face or shoulder n, which when the levers N are suitably rocked under the influence, respectively, of the cam-plates b b are adapted to contact with dogs 0, carried by the aforesaid levers O, wherefore they may rock the levers O. 7 It will be observed that in the case of both levers, however, there is considerable play between the faces n and the dog, so that for a large portion of the movement of the levers nov movement whatever is transmitted to the levers O. The object of this arrangement is to allow the slide M to be entirely under the influence of only one lever O at a time, for it will of course appear that as these levers O are connected through pins m and slots 0 it would be impossible to move the slide without moving both the levers 0. Hence it is seen that either of the levers 0 may be operated at the proper interval by its corresponding camplate and by means of the slots and pins referred towill cause the slide with the table and tools to be advanced or withdrawn. In the operation of automatic-tools of this class it frequently happens that the mechanism presses the cutting-tool with too great a force upon the work, which often results in the breaking and destruction of the tool or the work. I have endeavored to overcome this difficulty by arranging the dogs or projections 0 so that they will break under a strain that might be destructive at the tool. Hence before any accident happens at the tool the projection or dog gives way, calling the attention of the operator to the defect at the tool. The broken dog is of course then replaced by another and, the trouble at the tool overcome, the operation proceeds. These dogs may be of differentkinds adapted to break under different strains corresponding to predetermined strains at the tool due to the operation of the tool in different classes of work. i

I provide one more automatically-operated tool. This tool is indicated by the letter P, and it is mounted vertically at (L7 in the for ward part of the housing a, in which it is guided. A helical spring 2) normally maintains it in an elevated position, and the slide p, in which this tool is mounted, is provided at its rear with a small friction-roller 1) A standard 111', mounted upon the aforesaid table m, carries an arm in", which projects to a point adjacent to this friction-roller, where it is provided with a cam-shaped projection m upon its face, the form of which in outline is shown clearly in Fig. 5. As this arm in. advances and recedes with the movement of the table in the periphery of the cam-like projection m contacts with the aforesaid fric-' tion-roller p and as this contact proceeds along the forward face of the aforesaid periphery the friction-roller will be depressed, carrying with it the slide and tool. Furthermore, when the arm or has been so advanced that the frictional roller passes the point m it will be no longer held down and will then be immediately withdrawn by the extension of its aforesaid spring 19.

Having described that part of my invention which relates to the different devices for operating upon the work, I will now proceed to describe the gearing for driving the main shaft of the machine and the device in connection therewith for operating said shaft at different speeds to meet the several demands. This portion of the invention forms no part of this application, but is set forth in an application filed by me September 2, 1902, Serial No. 121,73

The main shaft 13 is provided on its extremity, as shown clearly in Figs. 1 and 3, with a worm-wheel 6 above which wormwheel is mounted a worm Q, adapted to cooperate with the same to drive the main shaft. This worm is carried by the short spindle q, to which spindle is rigidly secured a ratchetwheel g. This spindle q carries loosely a worn'i-wheel which rigidly carries a hub (f, which lies between the said worm-wheel and the said pinion q. To this hub g is rigidly secured a disk (1. This disk and the parts immediately connected with the same are clearly shown in Fig. 10. It is provided with a radial slot q, in which slot is mounted a little block-pawl g, which is pressed i11- wardly by a spring (1 so that its point (1 may engage the teeth of the aforesaid pinion q. The face of this block-pawl is provided with a laterally-projecting pin g which pin is adapted to lie within the curved slot carried by the hamtwheel g". This slot is clearly shown also in Fig. 1, in which figure the pin is shown lying at the innermost point of said slot. This hand-wheel, it may be said, is loosely mounted upon the spindle q, and it will readily appear that if it were turned to the right the slot (1 would cooperate with the pin (1 to throw the block-pawl q out of engagement with the ratchet-wheel q. From the construction described it will be apparent that by means of the hand-wheel g the aforesaid worm-wheel can be connected, through the pawl connection, with the spindle q, so that the worm Q could be rotated and drive the main shaft B. lVhen disconnected, the worm may be turned by the hand-wheel g. This worm-wheel meshes on its lower side with a second worm R, the shaft 1' of which is provided at one extremity with a bevel-gear 0", which bevel-gear meshes with a bevel-gear .9, carried by the spindle S. This spindle S, together with the parts intimately connected with it, is shown clearly in Fig. 6, where it will appear that the spindle is provided with a sleeve 3, feathered to it, and other sleeves s 5 the extemities of which are provided with clutch-teeth s and are mounted in bearings u These sleeves constitute, in fact, the hubs of gears indicated respectively by s 8 The sleeve s -is provided at its ends with heads 5 which heads are adapted to be rigidly secured to the same and are provided with teeth 3, which may cooperate with the said clutch-teeth carried by the aforesaid sleeves 3 3 A shifting collar 5 rigid with this inner sleeve, affords means for sliding the same longitudinally upon the shaft, so that one of the heads 8 may become disengaged from the sleeve with which it cooperates, the opposite head being at the same time thrown into engagement with that sleeve with which it cooperates. From this construction it will appear that either of the gears s 5 may be connected so that it will be possible to drive the spindle S through it. Gears if t, which mesh with the gears s s, as described, are rigid with and v adapted to be driven by the belt-pulley T, and these gears bear different speed relations to each other, wherefore the spindle S may be driven at different speeds. I provide means also for driving the worm Q independently of the worm-wheel (1 This I do in a simple manner by means of the pinion q, rigidly mounted upon the extremity of the spindle g, which meshes with a driving-pinion to, meshing with a second pinion a, which last pinion is rigid with and adapted to be driven by the belt-pulley U. Of course this latter means of driving can only operate when the aforesaid ratchetand-pawl connection has been thrown out, the worm-wheel 1 being then disconnected from the spindle q. I shall now describe the means for operating the sleeve.

Referring especially to Figs. 6 to 9, a shoe V (also shown in Fig. 2) lies about the shifting-collar 5 and this shoe is secured to a plate 4. slotted at 22 about the pin a wherefore it is guided horizontally in the frame A. To this plate is attached a draw-link 2), which makes a pin-and-slot connection at r with a lever 0 as shown most clearly in Fig. 9, and evidently by operating this lever 01 the shoe V may be moved in either direction and will close or open either of the clutches shown in. Fig. 6. A very similar arrangement is adopted for controlling the shifting of the belt on the pulleys U and T. A shifting-yoke NV, which surrounds the belt in the usual manner, is secured to a plate 20, which plate is guided also upon the frame and is provided with a pin-and-slot connection it" with the same. To this plate is pivoted a draw-bar 10 which makes a pin-andslot connection at the point 10 with a lever 20 which is pivoted to the frame at w, as indicated. Now, evidently moving this lever may shift the belt as desired. I provide for automatically operating these levers 1;" 10*. Referring especially to Figs. 1 and 9, it will be seen that the large cam-wheel b is provided on one of its edges with adjustably-connected cams 6 which as the cam-wheel rotates are adapted to engage the friction-roller 10, which is carried upon the lower extremity of the lever e0 There may of course be as many of these cams as desired, and their arrangement and disposition about the cam-wheel would be such as to cause the belt to be shifted at the proper moment. A camdisk Z7 upon which are mounted the adjustable cams U aiiiords means for automatically operating the lever o through the friction-roller '11", carried near its lower extremity. These cams 6 may be of course disposed in Whatever manner is necessary to secure the shifting of the belt whenever desired.

As shown in Fig. 5, at a point beneath the work the frame is provided with a shelving or inclined upper face, as indicated at y, so that the chips taken off by the tools will fall upon the same and be deflected to the side, so that they will not fall upon the running mechanism of the machine and endanger the cams and the other parts cooperating with them.

\Vhatl claim-is- 1. In a screw-machine, in combination, a transversely-guided carriage, a plurality of tools carried thereby, a spring normally constraining said carriage in one position, a camwheel provided with adjustable cams adapted to advance said carriage step by step so that said tools may operate successively upon the work, and other adjustable cams mounted upon said cam-wheel for retarding the return of said carriage, substantially as described.

2. In a screw-machine, in combination, a transversely-guided carriage, a plurality of tools mounted upon said carriage, frictionrollers on said carriage, a series of adjustable cams arranged to successively engage said friction-rollers on said carriage, a spring normally constraining said carriage and adapted to return the same to its normal position, and a second series ofadjustable cams adapted to be engaged successively by said friction-rollers upon the return of said carriage whereby the return of the same is retarded, substantially as described.

8. In a screw-machine, in combination, a transversely-guided carriage, a plurality of heads carried thereby, friction-rollers mounted on said carriage, a spring normally co11 straining said carriage and adapted to return the same to its normal position, a cam-wheel, a series of adjustable cams carried thereby which are arranged to engage said frictionrollcrs in succession and advance said carriage, a second series of adjustable cams carried by said cam-wheel for engaging said friction-rollers in succession upon the return of said carriage and retarding the return of the same, substantially as described.

4. In a screw-machine, in combination, a transverselyguidcd carriage, a plurality of tools carried thereby, friction-rollers also carried by the same carriage, a cam-wheel, cams carried thereby, one of said frictionrollers being arranged to lie in the path of said cams when said carriage is in its normal position, said cams being disposed to move said carriage so that said friction -rollers are moved successively into the path of said cams, substantially as described.

5. In a screwmachine, in combination, a transversely-movable carriage, a plurality of tools mounted thereupon, friction-rollers also carried by said carriage, a plurality of cams, said cams being adapted to engage said rollers, means whereby said friction-rollers successively engage the corresponding cams, automatic means for locking said carriage against movement during the periods in which said rollers do not engage said cams, the corresponding successive positions of said carriage permitting the successive operation of said tools upon the work, substantially as described.

6. In a screw-machine, in combination, a transversely-guided carriage, a plurality of tools mounted thereupon, means for moving said carriage into successive positions so that all of said tools may operate upon the work, a yielding device for returning said carriage, a device for locking said carriage against movement when in said successive positions, adjustable cams adapted to withdraw said locking device and to retain it withdrawn during each successive movement of said carriage, other adjustable cams adapted to retard the return of said carriage and an adjustable cam for holding said locking device out of engagement with the carriage during its return, substantially as described.

7. In a screw-machine, in combination, a movable carriage, movable heads mounted thereupon, means for advancing said heads from said carriage, a dog adapted to aline with said heads, a spring normally constraining said dog in a retracted position, and means for advancing said dog to return said heads, substantially as described.

8. In a screw-machine, in combination, a movable carriage, tool-heads mounted thereupon, means for advancing said tool-heads, a dog-for returning said heads, means for normally constraining it in an extreme position, and means for operating said returning-dog, substantially as described.

9. In a screw-machine, in combination, a movable carriage, movable heads mounted thereupon, means for advancing said heads from said carriage, a dog for returning said heads, means for constraining said dog in a retracted position, cams provided to advance said dog and return said heads, substantially as described.

10. In a screw-machine, in combination, a movable carriage, movable heads mounted thereupon, mechanism for advancing said heads from said carriage, a dog for returning said heads, a plunger carrying said dog, means for constraining said plunger in a retracted position, cams provided to advance said plunger and return said heads, and means whereby said advancing mechanism for said heads and said returning-dog may be so adjusted that there is no lost motion between them, substantially as described.

11. In a screw-machine, in combination, a movable carriage, movable heads mounted thereupon, means for advancing said heads from said carriage, a returning-dog for said heads, a plunger carrying said dog, means for constraining said plunger in a retracted position,an (1 adjustable cams provided to advance said plunger and return said heads, substantially as described.

12. In a screw-machine, in combination, a movable carriage, movable heads mounted thereupon, means for advancing said heads from said carriage, a return-dog forsaid heads, a plunger carrying said dog, .means for constraining said plunger in a retracted position, a cam-wheel having a circumferential groove on the face thereof, and cams provided with suitable blocks which are adapted to be secured in said groove, substantially as described.

13. In a screw-machine, in combination, a movable carriage, movable heads mounted thereupon, means for advancing said heads from said carriage,a return-dog for said heads, a plunger carrying said dog, means for constraining said plunger in a retracted position, a cam-wheel having a T-shaped circumferential groove on the face thereof, and cams provided with suitable blocks which are adapt ed to be secured in said groove, substantially as described.

let. In a screw-machine, in combination, a movable carriage, movable heads mounted thereupon, means for advancing said heads from said carriage, a return-dog for said heads, a plunger carrying said dog, a spring for constraining said plunger in a retracted position, a cam-wheel having a T-shaped circumferential groove on the face thereof, and cams provided with suitable blocks which are adapted to be secured in said groove,-s'ubstantially as described.

15. In a screw-machine, incombination, a transversely-movable slide, pivoted levers connected therewith, dogs carried thereby, other pivoted levers, cams controlling said other levers, said first levers having shoulders in the path of movement of said dogs, substantially as described.

16. In a screw-machine, in combination, a slide, a pivoted lever, a pin-and-slot connection between said slide and said lever, said lever having a projection, another pivoted lever having a shoulder in the path of movement of said projection, and cams controlling said last levers, substantially as described.

17 In a screw-machine, in combination, a transversely-movable slide adapted to carry tools, pivoted levers having a pin-and-slot connection with said slide, other pivoted levers, cams controlling said second levers, shoulders carried by said second levers, frangible projections carried by said first levers adapted to contact therewith, said projections afiording means for holding atool carried by said slide upon the guides, said projections being adapted to break undera predetermined strain, substantially as described.

18. In a screw-machine, in combination, a tool slidably mounted and adapted to project so as to engage the work, a spring restraining said tool in an inoperative position, an arm having a cam-surface, a friction-roller carried by said tool and adapted to contact therewith, and means for reciprocating said arm, substantially as described.

19. In a screw-machine, in combination, a tool slidably mounted, a spring normally constraining said tool in a retracted position, a friction-roller, an arm having a projection adapted to engage the same, a table carrying said arm, said table being slidably mounted, and means for moving said table, substantially as described.

20. In a screw-machine, in combination, a movable table, a standard carried thereby, an arm adj ustably carried by said standard, said arm having a cam-like projection, a tool slidably mounted, a spring normally constraining said tool in a retract-ed position, a friction-roller carried thereby and adapted to engage said cam-like projection to advance said tool, and means for moving said table, substantially as described.

In testimony whereof I hereunto aftix my signature in the presence of two witnesses.

FRANK L. TODD.

IVitnesses:

E. B. GILCHRIST, F. D. AMMEN.